Is Mormonism the only source of this belief? I just googled this and learned it may have been an early Christian teaching:
'The idea is not new. According to historian Elaine Pagels,*“the claim that Adam and Eve’s sin was to engage in sexual intercourse” was “common among such [second-century] Christian teachers as Tatian the Syrian, who taught that the fruit of the tree of knowledge conveyed carnal knowledge.” Also, to Christendom’s Church Father Augustine of the fifth century*C.E., sin had its beginnings in sexual desire on Adam’s part. In fact, Psychology Today said “Adam’s sin was carnal knowledge.” from Christian forum site .com
In read the Wikipedia page on Titian and found no mention of Sex as the forbidden fruit, but it does say one of his writings described matrimony as an invention of the devil. Also he was celibate.
My dear friend. Have you ever read Genesis, first book in the Bible, chapter 2?
I encourage you to read the actual Bible more and internet web sites less.
Genesis 1 says in sentences (verses) 16 & 17........
"the LORD God commanded the man, 'You are free to eat from any tree in the garden;
but you must not eat from the tree of the knowledge of good and evil, for when you eat of it you will surely die.'"
Now there it is! God saying NOTHING about Adam and Eve NOT HAVING SEX. He in fact commanded them to have children!!!! READ THE BOOK!
Adam and Eve one day listened to Satan (disguised as a serpent) who lied to them and told them: "'You will not surely die,' the serpent said to the woman. 'For God knows that when you eat of it your eyes will be opened, and you will be like God, knowing good and evil.'"
Satan told Adam and Eve a lie. He contradicted God's Word and said it was okay to eat from the forbidden tree.
The sin of Adam and Eve was disobeying God and doing what they wanted...instead of listening to God. They listened to Satan and their own reasoning, thinking God was keeping something wonderful from them, which He was not. And that's just like all of us. We think we know better than God. We think God is restricting us, keeping something from us, and we have a better way. Just like Adam and Eve, we are tempted to choose to believe Satan rather than believe God.